1. Field of the Invention
The present invention relates to a method for generating three-dimensional shape data, an apparatus for generating three-dimensional shape data, and a program for generating three-dimensional shape data of a three-dimensional object from a sketch of the three-dimensional object made by a designer or the like.
2. Description of the Related Art
Various methods have been described for generating three-dimensional shape data from a hand-drawn sketch by a designer or the like. For example, Japanese Patent Application Publication No. JP-A-6-149943, for example, describes a method for generating three-dimensional shape data from a perspective view (sketch) of the three-dimensional object on which cross-section lines are drawn by cutting the object with predetermined planes, and determining flat plane equations representing flat planes in a three-dimensional space in an orthogonal coordinate system from vanishing points and the like on the flat surfaces with respect to the perspective view, and then projecting the cross-section lines onto the flat planes represented by the flat plane equations.
Furthermore, Japanese Patent Application Publication No. JP-A-2004-206262, for example, describes a method of generating three-dimensional data by reading in a perspective view formed by a plurality of hand-drawn sketches and performing data processing.
In these examples, although the sketch drawn by a designer or the like has mathematically inaccurate perspective, three vanishing points are determined and the viewing point position and three-dimensional space are defined on the assumption that the perspective is correct. Thus, using the three-dimensional space defined in this matter, there is (1) a method of synthesizing a solid body using triangulation surveying from sketches from a plurality of different viewing line directions (views), (2) a method of creating a solid body by searching three-dimensional shape data similar to the perspective and adjusting to the perspective by deforming similar three-dimensional shape data using a neural network or the like, and (3) a method of synthesizing lines of the perspective with a single view made using a CAD (computer-aided design) method. These are described, for example, in Japanese Patent Application Publication No. JP-A-6-149943, Japanese Patent Application Publication No. JP-A-2004-206262, and also in Japanese Patent Application Publication No. JP-A-6-301751 and Japanese Patent Application Publication No. JP-A-10-269380.
A sketch made by a designer or the like is not drawn in accordance with an accurate orthogonal coordinate system. For this reason, the coordinate system of the sketch often has overall distortion in accordance with the image of the designer or the like. As described above, therefore, if three-dimensional shape data is generated in a three-dimensional space in an orthogonal coordinate system, there are cases in which the intent of the designer or the like is not reflected in the three-dimensional shape data.
That is, in the above-noted related art, the sketch made by the designer has mathematically inaccurate perspective. In the related art, however, the three-dimensional shape data is generated by searching for the optimal perspective for the case in which the sketch is viewed in the three-dimensional space, on the assumption that the sketch is a representation with accurate perspective. However, the sketch is not represented with accurate perspective. For this reason, in the above-noted related art there is the problem of three-dimensional shape data being generated that does not reflect the concept and the image of the designer as represented in the sketch.
In the above-described related art, although the three vanishing point method is used with regard to the definition of the coordinate system, because there is no vanishing point in the sketch, if the three vanishing point method is used, a large error occurs between the sketch and the three-dimensional shape data. For this reason, there is the problem of not being able to acquire three-dimensional shape data from a single sketch.
Also, because the structure represented by the lines of the sketch has no concept of a solid configuration, there is the problem of cases in which the solid body as seen in the sketch cannot be formed with three-dimensional shape data. Also, because the work flow of the method of generating three-dimensional shape data from a sketch is separate from the design work, there is the problem of it not being possible to correct and deform the three-dimensional shape data as the evaluation of the sketched design proceeds.